Windows RT Set-top Box.

Google has the Nexus Q

Device-q_medium

via www.google.com

Apple has the Apple TV

Step1-appletv-hero_medium

via store.storeimages.cdn-apple.com

The original Apple TV was released in 2007. It's currently in its 3rd iteration at the price tag of $99. Google on the other hand took almost four years to release a media streamer, the Nexus Q, which was ridiculously overpriced($299) for what it could do. I've never used a Google TV set-top box but from online reviews, it seems like it is a half-baked platform.

Since the cheapest Xbox costs $199, is it inconceivable for Microsoft to release a $99 set-top box running some variant of Windows 8?

Edited to replace WP8 with Windows RT.